Bloat is a digestive disorder of ruminants that develops as rumen microbes degrade readily available nutrients. The rapidly formed fermentation gases are trapped in the rumen digesta and produce a stable foam. The accumulation of this foam prevents eructation and the pressure from the trapped gas distends the rumen. Bloat is characterized as pasture or feedlot bloat depending upon the diet of the ruminant. Feedlot bloat develops when ruminants are fed large amount of grain which supply easily digestible carbohydrates from which excessive amounts of fermentation gases are produced. Pasture bloat is most commonly associated with the rapid consumption of large amounts of fresh green legumes.
Previous attempts to treat and cure bloat have included the administration of surface active compounds. For example, Shinozaki et al in U.S. Pat. No. 3,248,289 discloses the use of certain polyoxypropylene-polyoxyethylene polymeric non-ionic surfactants, Bartley et al in U.S. Pat. No. 3,465,083 discloses the use of a specific polyoxypropylene-polyoxyethylene surfactant known as poloxalene, and Myer et al in U.S. Pat. No. 3,686,416 discloses the use of a dimethyl dialkyl quaternary ammonium compound to control feedlot bloat.
It has also been proposed to treat bloat by the administration of antibiotics such as penicillin or combinations of penicillin and macrolide antibiotics such as erthromycin and tylosin as note Johnson et al, J. Animal Sci., Vol. 19, p. 739-744 (1960) and Hartman et al in U.S. Pat. No. 3,234,086.
Hahn et al in U.S. Pat. No. 3,868,448 disclose the prevention and treatment of bloat by administering an enzyme obtained from the fermentation of a specific Streptomyces griseus to the ruminant.
It has been suggested that protozoa present in the rumen may be a cause of bloat as note Clarke, Nature, Vol. 205, p. 95-96 (1965) and Kodras, Am. J. Vet. Res., Vol. 27, p. 629-632 (1966). Accordingly, numerous agents including antimalarials, anthelmintics, arsenicals, inorganic compounds, antibiotics and biocides, surface active agents, neuromuscular agents, hormonal agents, and cyclic nitrogen compounds were screened in vitro for antiprotozoal activity in ruminal fluid by Willard et al, Appl. Microbiol., Vol. 15, p. 1014-1019 (1967).